Air compressor system

ABSTRACT

In one aspect of the present invention, a compressor system includes a compressor shaft for generating compressed air, a clutch that, when engaged, transfers power from a vehicle engine to drive the compressor shaft and that, when disengaged, does not transfers power from the vehicle engine to drive the compressor shaft. An electric motor that, when activated, drives the compressor shaft. A control module that sets the compressor into one of at least three modes of operation as a function of respective statuses of various vehicle components. The compressor shaft is driven by both the clutch and the electric motor during at least one of the modes.

BACKGROUND

The present invention relates to a compressor. It finds particular application in conjunction with different modes of operating an air compressor and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.

Hybrid electric vehicles and vocational vehicles (e.g., utility trucks) utilize air for braking systems or tools when the vehicle engine is not running. Typically, an air compressor not driven by the vehicle's engine must be separately specified, which requires a space claim on the vehicle and associated wiring and plumbing. Specifying an additional compressor results in increased vehicle complexity and cost.

Compressors capable of being driven by both engine power and an on-board electric motor are known. However, none of the conventional compressors are capable of simultaneously being driven by a vehicle engine and an electric motor. In addition, no control system for setting a compressor in various modes of operation as a function of vehicle conditions is disclosed.

The present invention provides a new and improved apparatus and method which addresses the above-referenced problems.

SUMMARY

In one aspect of the present invention, a compressor system includes a compressor shaft for generating compressed air, a clutch that, when engaged, transfers power from a vehicle engine to drive the compressor shaft and that, when disengaged, does not transfers power from the vehicle engine to drive the compressor shaft. An electric motor that, when activated, drives the compressor shaft. A control module that sets the compressor into one of at least three modes of operation as a function of respective statuses of various vehicle components. The compressor shaft is driven by both the clutch and the electric motor during at least one of the modes.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which are incorporated in and constitute a part of the specification, embodiments of the invention are illustrated, which, together with a general description of the invention given above, and the detailed description given below, serve to exemplify the embodiments of this invention.

FIG. 1 illustrates a schematic representation of a vehicle including a compressor in accordance with one embodiment of an apparatus illustrating principles of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT

With reference to FIG. 1, a simplified component diagram of an exemplary vehicle 10 including an exemplary compressor 12 and associated control system are illustrated in accordance with one embodiment of the present invention. It is contemplated that the compressor 12 is a piston-type compressor, a screw-type compressor, a scroll-type compressor, or any other type of compressor.

The vehicle 10 includes an engine 14 and at least one vehicle battery 16. The compressor 12 includes a clutch 20, which is mounted to a mechanical drive port 22 on the engine 14. The clutch 20 is driven by mechanical power transmitted from the engine 14 via the drive port 22 whenever the engine 14 is running. The clutch 20 is mechanically connected to a shaft 24 of the compressor 12. A clutch control 26 (e.g., a clutch control valve) controls whether the clutch 20 is engaged or disengaged. More specifically, when the clutch 20 is engaged, the mechanical power from the engine is transmitted to the compressor shaft 24, via the clutch 20, for driving the shaft 24 to generate compressed air. For example, air generated by the shaft 24 is transmitted to a reservoir 30 where it is stored and compressed. When the clutch 20 is disengaged, the clutch 20 does not transmit mechanical power from the engine to the compressor shaft 24 and, therefore, the shaft 24 does not generate air for the reservoir 30.

In one embodiment, the clutch control 26 transmits a pneumatic signal to the clutch 20 via a pneumatic line 32. However, other embodiments in which other types of signals (e.g., electronic signals) are transmitted to the clutch 20 are also contemplated.

A motor 34 (e.g., an electric motor) is mechanically connected to the compressor shaft 24. Like the clutch 20, the motor 34 is capable of driving the shaft 24 to generate compressed air. The motor is driven by electrical power supplied via an electrical connection to the vehicle battery 16.

A control module 36 controls operation of the clutch control 26 and the motor 34. In one embodiment, the control module 36 is an electronic device that transmits electronic control signals to the clutch control 26 and the motor 34 via respective control lines 40, 42. More specifically, the control module 36 transmits a control signal to the clutch control 26 to engage the clutch 20 when it is desired to drive the compressor shaft 24 via the vehicle engine 14. Similarly, the control module 36 transmits a control signal to the motor 34 when it is desired to drive the compressor shaft 24 via the motor 34. Although the illustrated embodiment includes electronic control signals transmitted from the control module 36 to the clutch control 26 and the motor 34, it is to be understood that other embodiments, including other types of control signals (e.g., pneumatic) are also contemplated.

The control module 36 receives status signals from various sensors 44 associated with vehicle components representing respective vehicle functions. For example, the control module 36 receives status signals indicating a speed of the engine 14, a speed of the compressor 12, a speed of the motor 34, a pressure in the reservoir 30, an amount of charge on the vehicle battery 16, and/or whether vehicle service brakes are applied (e.g., whether a brake foot pedal is depressed). In one embodiment, the control module 36 receives electronic status signals from the various vehicle components. However, other embodiments including other types of control signals (e.g., pneumatic) are also contemplated.

The compressor shaft 24 is capable of being driven by the engine 14 (via the clutch 20) and/or the motor 34. The control module 36 transmits the respective control signals to the clutch control 26 and the motor 34, as a function of the status signals received from the various vehicle components, to set the compressor 12 into various modes of operation. As discussed in more detail below, the control module 36 automatically chooses a compressor 12 operating mode as a function of the status signals received from the various vehicle components.

In one embodiment, the control module 36 sets the compressor 12 to operate in one of a plurality (e.g., three (3)) modes i) an Active Clutch mode, ii) a Compressor Assist Mode, and iii) an Electric Drive mode.

The Active Clutch mode of operation is the traditional mode of operation for a compressor having a clutch and may be selected while the engine 14 is running. During this mode of operation, the clutch 20 is engaged to load the compressor 12, and the clutch 20 is disengaged to unload the compressor 12. The Active Clutch mode provides energy savings when the compressor 12 is unloaded. The control module 36 may set the compressor 12 to operate in the Active Clutch mode when the engine 14 is running, but the charge available on the battery 16 is below a predetermined threshold.

The Compressor Assist mode of operation is a mode in which both the engine 14 and the motor 34 are used to drive the compressor 12. During this mode of operation, the clutch 20 is engaged to load the compressor 12. At the same time, the motor 34 provides additional assistance for driving the compressor 12 for reducing load on the engine 14. When the clutch 20 is disengaged, the motor 34 similarly stops providing any assistance for driving the compressor 12, and the compressor 12 is unloaded.

While in the Compressor Assist mode, as the compressor 12 works to deliver compressed air to the reservoir 30 (e.g., the vehicle air system), the motor 34 draws energy from the vehicle battery 16 to assist in driving the compressor shaft 24. As discussed above, this assistance reduces a load on the vehicle engine 14. The assistance provided by the motor 34 drives the compressor shaft 24 such that any disruption to a drive train of the engine 14 is reduced and/or minimized. For example, any gear lash in the drive train of the engine 14 would not be reversed when the motor 34 is assisting the compressor shaft 24.

It is contemplated that during the Compressor Assist mode, the control module 36 selectively varies the amount of engagement of the clutch 20 and the amount of activation of the motor 34 as a function of a speed of the engine and the charge on the engine battery. The amount of clutch 20 engagement and motor 34 activation is set by the control module 36 to optimize performance of the compressor 12.

The Compressor Assist mode is advisable when the compressor 12 is in a loaded mode and the vehicle battery 16 is charged above a predetermined charge threshold. In one embodiment, the Compressor Assist mode is used when the compressor 12 is loaded and the vehicle battery 16 is charged above about a 90% charge threshold. Although about a 90% charge threshold is contemplated in one embodiment, it is to be understood that other embodiments in which the compressor 12 is set to the Compressor Assist mode at other charge thresholds are also contemplated. This mode of operation typically offers the most benefit during periods of high demand for compressed air and frequent brake applications (e.g., intra-city driving).

The Electric Drive mode of operation is a mode during which the compressor 12 is driven solely by the motor 34. During this mode of operation, the clutch 20 is disengaged so that the compressor shaft 24 is not driven by the engine 14. This mode of operation is useful when there is a demand for pressurized air, but the pressure in the reservoir 30 is below a predetermined pressure threshold and the engine 14 is not running. In one embodiment, the predetermined pressure threshold is about 120 psi. Although about a 120 psi pressure threshold is contemplated in one embodiment, it is to be understood that other embodiments in which the compressor 12 is set to the Electric Drive mode at other pressure thresholds are also contemplated.

A demand for air when the engine 14 is not running can occur, for example, in an electric/hybrid vehicle when the vehicle is running solely on electric power. This condition may also occur on a conventional (e.g., non-hybrid) vehicle (e.g., a utility truck or repair vehicle) that requires compressed air for systems in addition to a braking system.

In an alternate embodiment, the electric motor 34 also acts as an electric generator. In this embodiment, it is possible for the compressor 12 to operate in an additional mode of operation. More specifically, the compressor 12 may operate in an Energy Storage mode. During this mode of operation, engine braking power is used to drive the compressor 12 as well as generate electrical power to charge the vehicle battery 16. In this embodiment, it is contemplated that the compressor 12 operates as a head unloaded compressor so that the motor 34 is capable of providing electrical power to the compressor shaft 24 independent of whether the compressor 12 is loaded/unloaded (e.g., independent of whether the clutch 20 is engaged/disengaged).

While the compressor 12 is in the Electric Drive mode, if both the air system and electrical system are charged above respective predetermined thresholds at the time a vehicle brake (e.g., a vehicle service brake) is applied, the clutch 20 is disengaged to unload the compressor 12 while the motor 34 is used to assist braking through engine retardation.

Although the embodiments described above include electrical components such as the control module 36, the motor 34, and the clutch control valve 26, it is to be understood that other embodiments including hydraulic components in place of the electrical components are also contemplated. For example, a hydraulic pump and motor may be substituted for the motor 34.

The present invention describes a compressor 12 that is mounted to, and driven by, the engine 14 on the vehicle 10. In addition, the compressor 12 may be electrically driven by the vehicle battery 16 when the engine 14 is not running. High fuel prices and other factors are driving fuel economy improvements and the development of hybrid electric vehicles. One advantage of the embodiments of the preset invention described above are that the clutch technology produces fuel economy improvements while keeping the benefits of an engine mounted compressor. Although hybrid electric vehicles may still include a diesel engine, the compressor is advantageously capable of being electrically driven and mounted remotely from the engine because the engine does not run continuously. Combining a clutch and electric drive components on a single compressor has only recently been possible.

Specifying an electrically driven compressor on a vehicle requires a space claim on the vehicle frame. Such a compressor also requires mounting and isolation along with oil and filter maintenance. Mounting a compressor to an engine of the vehicle (as opposed to the frame) saves the space and isolation requirements on the vehicle frame and, furthermore, does not require special maintenance. These benefits translate into cost savings for engine/electrically driven compressors mounted to an engine (e.g., a hybrid engine) relative to frame mounted electrically driven compressors.

Advantages of the embodiments of the present invention include added convenience and simplicity associated with engine driven compressors while providing an air compressor that is capable of operating as engine driven, electrically driven, or a combination of both engine and electrically driven. The embodiments of the present invention are contemplated for use with hybrid electric and utility vehicles where compressor operation is desired when the engine is not running. An engine driven compressor offers ease of installation and efficient operation when the engine is running, while electrically driven compressors are completely independent of the engine and offer various operational advantages. The embodiments of the present invention operate the compressor in whichever mode is advantageous the operating condition. It simplifies the compressor installation while improving fuel economy beyond that of a compressor clutch alone and creates a compressor that can be operated when the engine is not running as is desired with hybrid/electric drive trains and utility vehicles.

While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details, the representative apparatus, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant's general inventive concept. 

1. A compressor system, comprising: a compressor shaft for generating compressed air; a clutch that, when engaged, transfers power from a vehicle engine to drive the compressor shaft and that, when disengaged, does not transfers power from the vehicle engine to drive the compressor shaft; an electric motor that, when activated, drives the compressor shaft; and a control module that sets the compressor into one of at least three modes of operation as a function of respective statuses of various vehicle components, the compressor shaft being driven by both the clutch and the electric motor during at least one of the modes.
 2. The compressor system as set forth in claim 1, wherein: during a first of the modes of operation, the clutch is engaged to drive the compressor shaft while the electric motor is not activated.
 3. The compressor system as set forth in claim 2, wherein: the control module sets the compressor in the first mode of operation when a status of an engine vehicle component is running, but a charge available on an engine battery vehicle component is below a predetermined threshold.
 4. The compressor system as set forth in claim 1, wherein: during a second of the modes of operation, the clutch is engaged to drive the compressor shaft while the electric motor is activated.
 5. The compressor system as set forth in claim 4, wherein: the control module sets the compressor in the second mode of operation when a status of an engine vehicle component is running and when a charge available on an engine battery vehicle component is at least a predetermined threshold.
 6. The compressor system as set forth in claim 5, wherein: the control module varies an amount of the clutch engagement and an amount of the motor activation as a function of a speed of the engine and the charge on the engine battery.
 7. The compressor system as set forth in claim 1, wherein: during a third of the modes of operation, the clutch is disengaged to not drive the compressor shaft while the electric motor is activated.
 8. The compressor system as set forth in claim 7, wherein: the control module sets the compressor in the third mode of operation when a status of an engine vehicle component is not running and when a charge available on an engine battery vehicle component is at least a predetermined threshold.
 9. The compressor system as set forth in claim 1, wherein: during a fourth of the modes of operation, the motor is activated to drive the compressor shaft independent of whether the clutch is engages; and the motor includes a generator that acts to generate electrical power generated when service brake of the vehicle is applied.
 10. The compressor system as set forth in claim 9, wherein: the generated electrical power charges the battery vehicle component.
 11. The compressor system as set forth in claim 10, wherein: if the air system is above a predetermined pressure level and the battery is above a predetermined charge when the service brake is applied, the clutch is disengaged to unload the compressor while the motor assists braking through engine retardation.
 12. The compressor system as set forth in claim 1, further including: a clutch control that transmits a control signal to the clutch for engaging/disengaging the clutch as a function of a control signal the clutch control receives from the control module.
 13. The compressor system as set forth in claim 12, wherein: the control signal transmitted from the clutch control to the clutch is a pneumatic signal; and the control signal transmitted from the control module to the clutch control is an electronic signal.
 14. A compressor system, comprising: a compressor shaft for generating compressed air into a reservoir; a clutch, mounted to a vehicle engine and the compressor shaft, that, when engaged, transfers power from the vehicle engine to drive the compressor shaft and that, when disengaged, does not transfers power from the vehicle engine to drive the compressor shaft; a clutch control communicating with the clutch, the clutch being engaged/disengaged as a function of a clutch control signal; a motor, mounted to the clutch, that, when activated, drives the compressor shaft; and a control module, communicating with the clutch control and the motor, setting the compressor into one of a plurality of modes of operation by transmitting respective control signals to the clutch control and the motor as a function of respective statuses of various vehicle components, the compressor shaft being driven by both the engine, via the clutch, and the motor during one of the modes.
 15. The compressor system as set forth in claim 14, wherein: the clutch control receives an electronic signal from the control module that indicates whether the clutch is to be engaged/disengaged; the clutch control communicates a pneumatic signal to the clutch, as a function of the electronic signal from the control module, for engaging/disengaging the clutch; and the motor receives an electronic signal from the control module that indicates whether the motor is to be activated.
 16. The compressor system as set forth in claim 14, further including: a vehicle battery electrically communicating with the motor, the vehicle battery providing electric power to the motor when the motor is driving the compressor shaft.
 17. The compressor system as set forth in claim 16, wherein: braking power generated when a vehicle service brake is applied is transformed by the motor into electrical power that is stored in the vehicle battery.
 18. The compressor system as set forth in claim 16, wherein: braking power generated when a vehicle service brake is applied assists braking through engine retardation.
 19. The compressor system as set forth in claim 14, wherein: the control module sets the compressor in the one mode of operation when a status of an engine vehicle component is running and when a charge available on an engine battery vehicle component is at least a predetermined threshold.
 20. A compressor system, comprising: a compressor shaft for generating compressed air; a clutch that, when engaged, transfers power from a vehicle engine to drive the compressor shaft and that, when disengaged, does not transfers power from the vehicle engine to drive the compressor shaft; a motor that, when activated, drives the compressor shaft; and means for setting the compressor into one of at least three modes of operation as a function of respective statuses of various vehicle components, the compressor shaft being driven by both the engine, via the clutch, and the motor in at least one of the modes.
 21. The compressor system as set forth in claim 20, wherein the means for setting includes: a control module that receives signals representing the respective statuses of the various vehicle components, the control module generating control signals for setting the compressor into one of the modes of operation as a function of received signals.
 22. The compressor system as set forth in claim 21, further including: a clutch control that receives one of the signals generated by the control module, the clutch engaging/disengaging as a function of a control signal transmitted from the clutch control that is based on the received signal from the control module.
 23. The compressor system as set forth in claim 22, wherein: the motor receives a control signal from the control module that activates/deactivates the motor.
 24. The compressor system as set forth in claim 20, wherein: the means for setting controls respective amounts that the motor drives the compressor shaft and that the clutch drives the compressor shaft as a function of the respective statuses of various vehicle components.
 25. The compressor system as set forth in claim 24, wherein: the vehicle component statuses include the engine speed, the speed of the compressor shaft, the speed of the motor, a pressure of the compressed air in an associated reservoir, a level of charge on a vehicle battery, and whether a vehicle service brake is applied.
 26. A method for driving a compressor, the method including: engaging/disengaging a clutch that transfers power from a vehicle engine to drive a compressor shaft; activating/deactivating a motor that drives the compressor shaft; receiving respective status signals into a control module from various vehicle components; generating control signals in the control module, as a function of the status signals, for engaging/disengaging the clutch and activating/deactivating the motor for selectively setting the compressor in one of a plurality of operating modes, the compressor shaft being driven by both the clutch and the motor during at least one of the operating modes.
 27. The method for driving a compressor as set forth in claim 26, wherein the step of engaging/disengaging the clutch includes: transmitting the control signal from the control module to a clutch control; and transmitting a clutch control signal, based on the signal transmitted from the control module, from the clutch control to the clutch.
 28. The method for driving a compressor as set forth in claim 26, further including: selectively determining respective amounts of the engagement of the clutch and of the activation of the motor as a function of the engine speed, the speed of the compressor shaft, the speed of the motor, a pressure of the compressed air in an associated reservoir, a level of charge on a vehicle battery, and whether a vehicle service brake is applied.
 29. The method for driving a compressor as set forth in claim 26, further including: charging a vehicle battery via the motor during a second of the operating modes. 